1. Technical Field
The invention relates to a process for recovering hydrocarbons from a subterranean hydrocarbon-bearing formation and more particularly to a process for improving conformance and flow profiles at or away from a well bore penetrating the formation.
2. Description of Related Art
Poor vertical conformance results from the vertical juxtaposition of relatively high permeability geologic zones to relatively low permeability zones within a subterranean formation. Poor areal conformance results from the presence of high permeability streaks and high permeability anomalies within the formation matrix, such as vertical fractures and networks of the same, which have very high permeability relative to the formation matrix. Fluids generally exhibit poor flow profiles and sweep efficiencies in subterranean formations having poor vertical or areal conformance. Poor conformance is particularly a problem where vertical heterogeneity and/or fracture networks or other structural anomalies are in fluid communication with a subterranean well bore across which fluids are injected or produced.
A number of conformance correction treatments exist. U.S. Pat. Nos. 3,909,423 and 4,110,230 to Hessert et al disclose gel compositions and processes for using the gels for conformance correction treatments. Unfortunately, the properties of such gels taught in the art are extremely sensitive to variations in gelation parameters such as gel component concentrations. It is usually necessary to preliminarily design a gel treatment in a laboratory under idealized conditions before the gel treatment can be employed in the field. Even so, it may be impossible to design an effective gel treatment because a hostile gelation environment may require a gel having component concentrations outside the operable ranges of a given process.
A present need exists for a conformance correction process employing a gel which is relatively insensitive to variations in specific gelation parameters which are required by oil field conditions. A process is needed for preparing a gel across a broad range of gel component concentrations without sacrificing the ability of the gel to meet the performance demands of differing subterranean formations.